The planned studies will be a continuation of ongoing projects that reflect a long interests in normal and abnormal growth regulation in the human hematopoietic system. The specific projects include: 1) Cytogenetic and molecular genetic studies in hematopoietic neoplasia. Long-term chromosome studies of the chronic B cell and T cell neoplasms will be extended, to determine their diagnostic and prognostic value and to provide material for ongoing colloborations, with Dr. Carlo Croce, on specific oncogenes involved in the pathogenesis of these disorders and mechanisms of altered gene regulation. 2) Continuation of related studies on chromosomal abnormalities in adult and childhood nonlymphocytic preleukemia, including hemic disorders associated with atypical chromosomal fragility syndromes. These studies will also extend to the molecular level, investigationg genes critically involved in certain nonlymphocytic preleukemias and leukemias. 3) An Additional group of continuing related studies of growth regulation in normal lymphocytes, focusing on the role of interleukins (IL1, IL2) in the "triggering" of normal human T cells. Various stimulators and inhibitors of T cell proliferation will be used to investigate further the biological pathways involved and related expression of specific genes and proto-oncogens.